Failed tx emissions again(update)

Posted By: 6packattk

Failed tx emissions again(update) - 05/11/11 04:25 AM

Need ideas on what to change beside O2 sensor,was worse,failed for hi nox in low and high range(failed last year too in high range only).Put new o2 sensor on it and took off egr and looked how dirty it was and pulled map sensor and checked it too but didnt change em.Guy at test place said catalytic convertor,this is second one on it,has 160,000 on it.May have to take to non emission state and sell it cause it still runs great,has 5.2 v-8 extended cab.Any techs feel free to chime in,thanks in advance.(91 dakota if that matters)

Posted By: 383man

Re: Failed tx emissions again - 05/11/11 06:52 AM

Make sure the EGR works right. The EGR is very important for reducing NOX. When it recirculates the hot burnt exh gasses back into the intake and into the cylinders it reduces the combustion chamber temps as the burnt gasses wont ignite and burn so the temps drop. Make sure the valve works and opens and make sure the passages are not blocked. Ron

Posted By: 1_WILD_RT

Re: Failed tx emissions again - 05/11/11 06:58 AM

Quote:

Make sure the EGR works right. The EGR is very important for reducing NOX. When it recirculates the hot burnt exh gasses back into the intake and into the cylinders it reduces the combustion chamber temps as the burnt gasses wont ignite and burn so the temps drop. Make sure the valve works and opens and make sure the passages are not blocked. Ron

Yup, EGR..

Posted By: 6packattk

Re: Failed tx emissions again - 05/11/11 01:44 PM

Thanks guys,question,what is best thing to use to clean passage under egr,I checked and valve opened on egr,but will probly just get a new one,but want to clean the port too before I put new on it.

Posted By: 3hundred

Re: Failed tx emissions again - 05/11/11 03:47 PM

My wife's '93 Ramcharger fails NOx pretty regularly, about every 5 years or so. Then we change the cat con and watch the numbers rise every year until it fails again.

The high speed test is usually okay, high but okay, it's the low speed that gets her. Other than failing emissions the truck runs great, pushing 300,000 miles pretty hard.

Robert

Posted By: None2Slow

Re: Failed tx emissions again - 05/11/11 03:52 PM

Somethimes you need to run a stiff wire down into the port for the egr. It gets blocked with carbon. Maybe use some carb cleaner along with the wire and ream it out. Then use a bottle brush after that.

Posted By: mr_340

Re: Failed tx emissions again - 05/11/11 04:11 PM

I had a 1990 Ramcharger with almost 250k miles on it. I had to back the timing back to TDC to get the NOx down to pass. It didn't make any power and I'd bump it back up to make it driveable again. Mopar has a combustion chamber cleaner that seemed to work well, but it didn't help the NOx numbers.

Posted By: 6packattk

Re: Failed tx emissions again - 05/11/11 05:39 PM

Thanks a bunch guys,left truck sit a year and I guess hoped it would heal itself.Ron cant wait to hear results of your new motor,I have one still in limbo a measly 446. Also I think my timing cannot be altered on the 91,Tbi with a notch on distributor base if I recall,I am probly gonna have to go with cat con #3.

Posted By: 383man

Re: Failed tx emissions again - 05/11/11 06:56 PM

Quote:

Thanks a bunch guys,left truck sit a year and I guess hoped it would heal itself.Ron cant wait to hear results of your new motor,I have one still in limbo a measly 446. Also I think my timing cannot be altered on the 91,Tbi with a notch on distributor base if I recall,I am probly gonna have to go with cat con #3.

Thanks as I hope it runs as good as I would like it too.

Actually you can set base timing on a 91 with TBI. You have to unplug the coolant sensor as that puts it in a limp mode and the timing wont change like that unless you turn the dist as you can do that and check or set base timing. The 92 and up SFI is where you cant set the timing but you can set the dist pick-up sync to crank signal. You either need a scan tool or DVM to set the dist sync signal on the 92's and up. Good luck , Ron

Posted By: 6packattk

Re: Failed tx emissions again(update) - 05/15/11 07:33 PM

It passed with only new o2 sensor and new egr,looked better at old egr and stem on bottom inside was gone,installed new one,it passed yesterday so even washed it.Now it gets new timing gears and chain(cloyes)new water pump and gaskets and any hoses it needs and I will have a newer better running truck.It had a water pump changed in parking lot like 8 years ago and had always overheated in traffic ever since.Also will correct air conditioning while front of engine is off.Thanks guys,thought you would like to know results.